1. Field of the Invention
This invention relates generally to tertiary petroleum oil recovery and, more particularly, but not by way of limitation, to an improved method and apparatus for injecting hot water into a partially depleted well for recovery of residual petroleum oil deposits.
2. Description of the Prior Art
Subsurface petroleum oil deposits are generally recovered via one of three methods. The primary method is commonly known as a "gusher" and is a spontaneously occurring phenomenon which sometimes results from a surface well being sunk into petroleum oil deposits containing a relatively large quantity of natural gases. The above method is generally rare, and short-lived, and is therefore not practical for commercial oil production. The secondary method of petroleum oil recovery is effected by creating an artificial pressure difference between the petroleum oil deposits and the atmosphere. This is generally accomplished via connecting a pump to a well head whereby the oil rises to the surface when the pump is in operation. The above method is regarded as practical and efficient but can be used to remove only a portion of the oil deposit contained in the subsurface formation. Tertiary methods must therefore be utilized to recover the remaining, or residual, portion of the oil deposit. Various methods have been proposed and utilized in the past and generally consist of injecting heated hydrocarbon gases, steam, water or various combinations thereof into the subsurface oil deposits. One particular method consits of injecting hot exhaust gases into a partially depleted well whereby the gases vaporize portions of the oil deposits and are pumped back to the surface for processing. Examples of this method are shown in the U.S. Pat. No. 1,342,741, issued to D. T. Day and U.S. Pat. No. 1,768,984, issued to L. J. Husted. Another method consists of injecting hot exhaust gases, in conjunction with steam and/or viscosity-lessening fluids, into a partially depleted well whereby the oil deposits are forced to adjacent recovery wells as shown in the U.S. Pat. Nos. 2,173,556, issued to H. W. Hixon and U.S. Pat. No. 2,813,583, issued to J. W. Marx, et al. A more recent method consists of injecting heated water into a partially depleted well whereby the oil viscosity is lessened and portions of the oil deposit are forced to adjacent recovery wells. Examples of this method are shown in the U.S. Pat. Nos. 3,186,484, issued to R. R. Waterman and U.S. Pat. No. 3,421,583, issued to D. S. Koons.
Generally related examples of the above recovery methods are shown in the following U.S. patents and references: U.S. Pat. No. 2,584,606, issued to E. S. Merriam, et al; U.S. Pat. Nos. 2,734,578 and 2,823,752, issued to H. Walter; U.S. Pat. No. 3,012,607, issued to C. L. De Priester, et al; U.S. Pat. No. 3,136,359, issued to T. T. Graham; U.S. Pat. No. 3,342,259, issued to H. H. Powell; U.S Pat. No. 3,360,044, issued to H. Lange; U.S. Pat. No. 3,386,508, issued to W. J. Bielstein, et al; and "Application of Heat for Recovery of Oil: Field Test Results and Possibility of Profitable Operation" by H. Walter published in the February, 1957 issue of the Journal of Petroleum Technology